@stefano Honestly - I can understand. I've seen production environments where every admin just fired up servers with distro he likes best. They had like 10 different (or more) Linux and BSDs, including different major versions, and so on.
And every time they had staff changes, some boxes were left orphaned with no maintainer. So it might be a reason behind the wish to use a certain distro, beside that argument they tried to give you.